The effect of the diuretics furosemide, ethacrynic acid, and the thiazides on corneal hydration and transparency will be studied. Active ionic transport is one of the possible mechanisms responsible for the maintenance of a normal corneal transparency. Chloride active transport has been found in frog and rabbit corneas as well as in a portion of Henle's loop in the kidney. Furosemide, ethacrynic acid and ouabain inhibit chloride transport. A correlation between the rate of chloride transport and transparency will be established in vitro using these diuretic agents. The presence of these diuretics in the aqueous humor associated with a possible alteration of the corneal thickness will be investigated in vivo.